The present invention relates to motor fuel additives.
To perform satisfactorily in modern, high performance automotive engines, today's gasolines must meet exacting specifications. Characterstics such as knock-resistance (indicated by octane number) and vaporizing curve must be tailored to meet the needs of the particular engines in which the gasoline will be used.
To prevent annoying, fuel wasting, potentially damaging engine knock at all engine speeds and loads, a good gasoline must have high anti-knock quality throughout its entire distillation range. In 1919 it was found that knock could be suppressed by the addition of tetraethyl lead and other alkyl lead compounds. However, leaded gasoline is being phased out due to the environmental problems associated with it. This lead to the development of another anti-knock additive, methylcyclopentadienyl manganese tricarbonyl (MMT). Unfortunately, the Environmental Protection Agency has also recently banned the use of MMT in gasoline.
Many other compounds have been considered as anti-knock gasoline additives. Specifically, alcohols such as methanol and ethers such as MTBE (methyl-tertiary-butyl ether) have been found to increase the octane number of gasoline. However, each of these compounds is disadvantageous for various different reasons.
Furthermore, it is important for fast warm-ups, smooth acceleration, and proper distribution of the fuel among the entire cylinders, that the gasoline vaporize at an increased rate as carburetor and manifold temperatures rise. Thus, gasolines need a mixture of low boiling components for easy starting and high boiling components for smooth acceleration and high mileage per gallon. This high mileage per gallon is a critical factor in the present-day gasoline market. Unfortunately, many of the prior art anti-knock additives are low boiling compounds.
It has now been discovered that aryl ethers are particularly effective anti-knock additives for gasolines. Specifically, the instant aryl ethers substantially increase the octane number of gasoline. Furthermore, their high boiling points will result in smoother acceleration and higher mileage per gallon of gasoline than prior art additives. Thus, the instant aryl ethers are likely to become an important part of future gasoline blends.